粗根韭的核型分化研究

A STUDY ON KARYOTYPE DIFFERENTIATION OF ALLIUM FASCICULATUM (LILIACEAE)

对葱属粗根韭的３个地方居群的核型分析结果表明，３个居群的核型表现出很大的差异。西藏达孜居群为２ｎ＝２ｘ＝２０＝４ｍ＋１０ｓｍ＋２ｔ（２ＳＡＴ）＋４Ｔ；四川乡城居群为２ｎ＝２ｘ＝２０＝１０ｓｍ＋６ｔ（２ＳＡＴ）＋４Ｔ；四川理县居群为２ｎ＝２ｘ＝２０＝６ｍ＋１０ｓｍ＋２ｔ（２ＳＡＴ）＋２Ｔ。虽然它们之间在核型上存在差异，但除达孜居群的植株较矮小外，３个居群的植物在形态上却非常一致。理县居群的核型被认为是原始类型，由它通过染色体结构变异，分别演化出更不对称的达孜居群和乡城居群。葱属中，目前只发现４个种的染色体基数为１０，除本种外其余３种分别是Ａ．ｄｅｃｉｐｉｅｎｓＦｉｓｃｈ．；Ａ．ｋｕｊｕｋｅｎｓｅＶｖｅｄ．和Ａ．ｃｈｅｌｏｔｕｍＷｅｎｄｅｌｂｏ。根据这４个种的核型特征和分布格局，基数１０可能有不同的起源，至少粗根韭的起源与其余３种不同，而且起源最晚。粗根韭的核型特征及它与染色体基数为１１的宽叶韭Ａ．ｈｏｏｋｅｒｉＴｈｗａｉｔｅｓ在核型上的相似性，表明它们很可能共同起源于基数为１０但现已绝灭的祖先种。此外。

Karyotypes of three local populations of Allium fasciculatum Rendle were analyzed. The karyotype of the population from Dagze of Xizang was 2n=2x=20=4m+10sm+4T+2t(2SAT), the one from Xiangcheng of Sichuan was 2n=2x=20=10sm+6t(2SAT)+4T,and the one from Lixian of Sichuan was 2n=2x=20=6m+10sm+2t(2SAT)+2T. Although there were differences in karyotypes among the three populations,they were very similar in morphological characters,except that plants in the Dagze population were lower. The karyotype of the Lixian population is considered to be a primitive one that has evolved into the more asymmetrical karyotypes of the Dagze population and Xiangcheng population by structural aberration. In the genus Allium, only four species, A. fasciculatum,A.decipiens Fisch.,A.kujukense Vved. and A.chelotum Wendelbo. have so far been found to have the basic chromosome number of x=10. According to karyotype characters and the distribution pattern of these four species,the basic number x=10 may have different origins. At least that of A.fasciculatum is different from that of the other three species and might have originated the latest. A.fasciculatum was similar to A.hookeri Thwaites (the latter has x=11) in karyotypical and morphological characters. Therefore, they are considered to have originated from a common extinct ancestor that had the basic number of x=10.